EOCENE AND OLIGOCENE TITANOTHERES OF MONGOLIA 



913 



with the barren beds above the Iran Dabasu. The Arshanto 

 may prove to be only the lower Irdin Manha, or it may be 

 separated from the Irdin Manha by a diseonformity. The base 

 of these beds has not been seen. 



The type locality of the Arshanto formation is 7 

 miles northeast of the Kalgan-Urga trail. The 

 Arshanto consists of reddish shales, which appear from 

 the latest faunistic evidence to belong to an earher 

 life zone, distinct from the Irdin Manha or Protitano- 

 iherium grangeri zone, yielding an abundance of 

 lophiodonts, which are found in the red shales at one 

 point. In the red shales to the north, at Iren Dabasu, 

 beds of the same appearance and presumably of the 

 same age, which overlie the Iren Dabasu Cretaceous, 

 yield a few scraps of lophiodont teeth. 



Fauna. — Small perissodactyls are abundant in these 

 beds and are described by Matthew and Granger 

 (1925) as Schlosseria, a lophiodont, and Teilhardia, 

 ■originally referred to the primitive rhinoceros family 

 of Hyracodontidae. 



BASAL EOCENE OR UPPER CRETACEOUS: GASHATO 

 FORMATION 



Berkey and Morris (October 7, 1924, pp. 117, 125) 



The Gashato clays and gravels, which are of basal 

 Eocene or Upper Cretaceous age, immediately over- 

 lying the Djadochta formation (Protoceratops zone), 

 carry an early Eocene fauna, according to field identi- 

 fications by Granger and careful revision by Matthew 

 ^nd Granger (1925). The known faunal Hst is as 

 foUows: 



Palaeostylops iturun. Order Notoungulata (ungulates of the 

 Southern Hemisphere). Notoungulates (Arctostylops) have 

 been discovered in Wyoming and in South America. 



Prionessus lucifer. Order Multituberculata (=multituber- 

 ■culates); also known in the Cretaceous and basal Eocene of 

 western Europe and of North America. 



Baenomys ambiguus. Order Glires; resemblances to both the 

 Simplicidentata and the Lagomorpha. 



Eurymylus laticeps. Order Insectivora?, Menotyphla? 



Phenacolophus fallax. Order Condylarthra?; archaic pen- 

 tadactyl ungulates. 



Hyracolestes ermineus. Order Creodonta; archaic carnivores. 



Sarcodon pygmaeus. Order Insectivora? 



The ancestral relationship of the Mongolian Palaeo- 

 stylops to the American Ardostylops of our lower 

 Eocene Wasatch formation is indicative of "Pale- 

 ocene" (basal Eocene, Torrejon) or Upper Cretaceous 

 age. The remaining species of multituberculates, 

 insectivores, rodents, and creodonts show no characters 

 precluding the possibility of "Paleocene" or basal 

 Eocene age, although these species do not represent 

 ancestors of the Eocene faimas of Europe or of North 

 America, as might have been expected. The absence 

 of ancestors to the higher ungulates, perissodactyls, 

 artiodactyls, and like forms points to this Gashato 

 fauna as a surviving archaic fauna of basal Eocene or 

 Upper Cretaceous age. 



HISTORY OF THE DISCOVERY OF REMAINS OF 

 TITANOTHERES IN MONGOLIA 



Among the first fossUs discovered in the Gobi Des- 

 ert in 1922 was a left lower jaw of a titanothere with 

 six grinding teeth (first premolar to second lower 

 molar), found by Prof. Charles P. Berkey in the 

 Irdin Manha formation on May 4, 1922. To this first 

 titanothere discovered in Mongolia is now assigned 

 the American Museum number 19179 and it is referred 

 to the species Protitanotherium grangeri, the type of 

 which was named from another specimen in honor 

 of Walter Granger, chief paleontologist of the expe- 

 dition. 



Kecognizing the great importance of this discovery, 

 the leader of the expedition, Roy Chapman Andrews, 

 immediately announced it by cable to the American 

 Museum: "First titanotheres discovered." This first 

 titanothere jaw found in the Irdin Manha formation 

 of Mongolia recalls the fact that Joseph Leidy, in 1852, 

 named the genus Titanotherium ( = Menodus) from a 

 similar fragment of a jaw found about 1846 in the 

 Badlands of White Eiver, South Dakota. The first 

 titanothere jaw was discovered in South Dakota in 

 1846; its Asiatic relative was discovered in the heart 

 of the Gobi Desert 76 years later, in 1922. 



The first titanothere jaw {Protitanotherium mongo- 

 liense, figs. 784, 789, 792) to reach the American 

 Museum, in the autumn of the year 1922, was found in 

 the Shara Miorun formation, which is more recent than 

 the Irdin Manha. It was immediately recognized by 

 the present writer as belonging to the genus Protitano- 

 therium and as directly intermediate in size between 

 Protitanotherium emarginatum and Protitanotherium 

 superhum, both of the upper Eocene Uinta formation 

 of Utah (level C of Uinta Basin). This determination 

 was pubhshed October 17, 1923, and the description 

 of the animal under the name Protitanotherium mon- 

 goliense was amply confirmed by discoveries made 

 during the season of 1923. 



Explorations in the Irdin Manha, Shara Murun, 

 and still more recent Ardyn Obo formations contin- 

 ued for two seasons (1922, 1923) and yielded altogether 

 remains of between 50 and 60 individual titanotheres, 

 among which are many exceptionally fine skulls and 

 jaws, numbering 45 in all, as listed below, and several 

 hmbs. After very careful shipment from the distant 

 desert and skillful laboratory work, done chiefly by 

 Messrs. George Olsen, Charles Lang, and Otto Falken- 

 bach, the collection was assembled for critical exam- 

 ination, measurement, and comparison with the Amer- 

 ican titanotheres of northern Utah, of Wyoming, and 

 of South Dakota, with most interesting results. 



In Mongolia seven genera of American titanotheres 

 are represented. Dolichorhinus , Telmatherium, Pro- 

 titanotherium, Menodus, and Brontops are certainly 

 identified; Manteoceras and Metarhinus are doubtfully 



